A solar cell assembly, also referred to as a fitted solar cell, is an electronic component that, when exposed to light (photons), produces electricity by virtue of the photovoltaic effect.
The electrical power obtained is proportional to the radiant power that is incident on the solar cell assembly and on the area of the solar cell assembly.
Photovoltaic cells are produced on a substrate or wafer, i.e. a crystal structure that is originally circular but then cut to the desired geometry, this structure also being referred to as a raw cell.
The photovoltaic cells are then fitted with interconnectors, covered with a cover glass, and fitted with a bypass diode, which is placed beside the photovoltaic cell in most technologies, to form a solar cell assembly.
A photovoltaic network is an assembly or layout of photovoltaic cells that are laid out side-by-side.
The energy efficiency of the photovoltaic effect decreases with increasing temperature, hence it is advantageous to keep a photovoltaic network as cold as possible to improve its efficiency.
FIG. 1 is a schematic illustration of one non-limiting example of a photovoltaic cell 1 in the shape of a semicircle, in which a protective glass 2 is cut to the same shape as the photovoltaic cell 1 and arranged on the photovoltaic cell 1 to form a fitted photovoltaic cell 3.
In the case of solar generators for space applications and for missions close to the sun, the problem of rising temperature and decreasing efficiency is solved by placing optical solar reflectors (OSRs, or mirrors) between the cells, as for example illustrated in FIG. 2, where rows 4 of fitted photovoltaic cells 3 akin to those of FIG. 1, but in this example semihexagonal in shape, and rows 5 of mirrors or OSRs are alternated.
The problem with such a solution is the decrease in active area and also the need to add components (OSRs or mirrors) to the network to lower the temperature. This is complex and expensive, and hence generally not applied to solar generators for missions in Earth orbits for which an additional cost such as this is too high with respect to the more limited heating of the photovoltaic cells with respect to a hot mission closer to the sun.